VFD beginner question.
VFD beginner question.
(OP)
Hello,
I'd like to know which measureaments are necessary to verify the rectifier module, capacitors and IGBT's of a VFD.
Thanks.
I'd like to know which measureaments are necessary to verify the rectifier module, capacitors and IGBT's of a VFD.
Thanks.





RE: VFD beginner question.
If it's a VFD under a few hp - just run it. If it has a problem with the IGBTs it will probably tell you. Use a clamp-on to see if the three phases supplying the drive are pretty close together. If they're not, but the voltages are the same, you have a bad rectifier.
You can do the same test with the outputs. The actual amp numbers will be complete and utter garbage but they should be very similar.
Keith Cress
kcress - http://www.flaminsystems.com
RE: VFD beginner question.
I posted this thread because I came across a case this week of a VFD displaying a short circuit fault message. When I replaced the output IGBTs, the drive stopped displaying this message and started working perfectly again.
The problem is that, when I measured them, they didn't appear to have anything uncommon. The test that i made was using a multimeter in diode scale.
Thanks,
Fabio Melo
RE: VFD beginner question.
Sometimes, at a test voltage of 1.5V, the short will not appear where, at operating voltage of 660VDC, it will. That's probably what happened with your drive. You did the right thing.
RE: VFD beginner question.
"Dear future generations: Please accept our apologies. We were rolling drunk on petroleum."
— Kilgore Trout (via Kurt Vonnegut)
For the best use of Eng-Tips, please click here -> FAQ731-376: Eng-Tips.com Forum Policies
RE: VFD beginner question.
Many modern meters deliberately test resistance at less than 0.6V to avoid forward-biasing any semiconductors. It is very easy to be misled - you need to understand the capabilities of the instruments.
----------------------------------
If we learn from our mistakes I'm getting a great education!
RE: VFD beginner question.
Keith Cress
kcress - http://www.flaminsystems.com